High (elevated) surfaces, which represent dead space, are commonly advantageously used for storage of objects of various different types. For example, it is common for ladders to be mounted on the top of firefighting vehicles and for these to be used in rescuing people when there is a fire. Naturally, each time that objects are loaded or taken down from these high (elevated) places, it is necessary to go up to this high place and pass the objects up and down, which is bothersome and may be dangerous. A particular problem occurs in the case of rescue ladders mounted on the top of vehicles, as described above, in that it is not possible to take the ladder down quickly, even if there is an urgent need to use the ladder. Lift devices can also be used for loading and unloading objects, but conventional lift devices generally use hydraulic systems or the like to move loading platforms straight up and down. With this type of lift device, it is necessary for a person to move the objects between the loading platform and the high surface. Furthermore, crane systems are capable only of reducing human labor, and cannot be expected to greatly reduce the time required for loading and unloading; nor are these systems suitable for firefighting and the like, where speed is important.
Japanese Laid Open Patent Application No. JP-2001-163599-A describes the development and use of a lift device in which a carrier, bearing various types of objects, is lowered at an inclination from a high surface, such as the top of a vehicle, by swinging a swing arm.
However, while the previously developed lift device is useful in that it allows objects such as rescue ladders used by firefighting vehicles and the like to be quickly and easily loaded or unloaded without going up onto the top surface of the vehicle, when the high surface is particularly high, or the length of the carrier is increased to accommodate long objects such as ladders, the length of the swing arm must be increased by a corresponding amount. This presents a disadvantage in that, if the swing arm is long, the swing diameter thereof increases so that, when working in an enclosed space having a low ceiling or beneath overhead wires, the top of the carrier may collide with obstacles such as ceilings or overhead wires when the swing arm is swung.
Furthermore, if an obstacle is present directly below the high surface, it is not possible to lower the carrier from the high surface, because the bottom of the carrier will collide with this obstacle.